Formation of asymmetric phospholipid membranes via spontaneous transfer of fluorescent lipid analogs between vesicle populations

作者：Richard E. Pagano, Ona C. Martin, Alan Jay Schroit, Douglas K. Struck · 发表于：Biochemistry · 年份：1981 · DOI：10.1021/bi00520a018 · 被引用次数：99 · 研究领域：Lipid Membrane Structure and Behavior、Lipid metabolism and biosynthesis、Fatty Acid Research and Health

A method is presented for generating artificial lipid vesicles bearing an asymmetric distribution of either of the fluorescent lipid analogues 1-acyl-2-[6-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]caproyl]phosphatidylcholine or 1-acyl-2-[12[(7-nitro-2,1,3-benzoxadiazol-4-yl]amino]dodecanoyl]-phosphatidylcholine, in which the fluorescent lipid is located predominantly in either the outer or inner leaflet of the vesicle bilayer. The procedure is based on the observation that these lipid analogues undergo rapid spontaneous transfer (exchange) between vesicle populations [Nichols, J. W., & Pagano, R. E. (1981) Biochemistry 20, 2783-2789]. When an excess of nonfluorescent acceptor vesicles is mixed with small unilamellar vesicles containing 5 mol % fluorescent lipid, approximately 50% of the fluorescent lipid is transferred to the acceptor vesicles, whereas if fluorescent multilamellar vesicles are used, only approximately 10% of the analogues is available for transfer. These fractions of fluorescent lipid available for intervesicular transfer correspond closely to the amount of phospholipid residing in the outermost leaflet of the donor vesicles, suggesting that only fluorescent lipids present in the outer surface of the vesicles can spontaneously transfer between vesicles populations. Evidence demonstrating that the movement of the fluorescent lipid between vesicle population is the result of a net transfer process rather than lipid exchange is also presented. A novel assay based...